Apparatus for cleaning and grading asbestos



Feb. 13, 1962 J. D. CHRISTIANl APPARATUS FOR CLEANING AND GRADINGASBESTOS Filed March 25, 1960 2 SheetsSheet 1 a ff @wa-ava,

Am-v 'FE- 'n /NVENTO/P JOHN D. CHR/SWAN ATTORNEYS Feb. 13, 19623,021,008

J. D. CHRISTIAN APPARATUS FOR CLEANING AND GRADING ASBESTOS Filed March23, 1960 2 Sheets-Sheet 2 /N VEN TOR JOHN D. CHR/ST/AN ATTORNEYS UnitedStates Patent Utilice 3,021,008 Patented Feb. 13, 1962 3,021,008APPARATUS FOR CLEANING AND GRADING ASBESTOS John D. Christian, Toronto,Ontario, Canada, assigner to Y Cassiar Asbestos Corporation Limited,Toronto, 9ntario, Canada Filed Mar. 23, 1960, Ser. No. 17,082 3 Claims.(Cl. 209-499) present time, this grading has largely been carried out'by use of fiat shaker screens and to a lesser extent, by using rotarytrommels. In the first case, the screens required result in bulkyapparatus which is extremely heavy, costly, and promotes vibration ofthe building in which they are situated and require a great deal of oorspace. Moreover, such flat screens are subject to blindingj i.e.clogging, and require frequent cleaning, which of course results instoppages as well as screen wear. In the second case, trommels-inclinedcylindrical rotating screens in which the material is subjected totumbling-will not in terms of comparative screen area operate aseiiiciently as liat screens and they are likewise subject to blinding lnboth cases the grade of product is not as goed.

These disadvantages are largely eliminated by the apparatus of thepresent invention which, in terms of screen area, have approximatelythree times the capacity of the at screen apparatus to do the same workwhile taking up approximately one-quarter of the space, consuming aboutiifty percent less power and involving approximately fifty percent lessweight whereas the difficulty of blinding and work stoppage as well asscreen wear is greatly reduced. Due to increased eliiciency of thescreen, either smaller screen meshes may be used to remove the samequantity of dust and shorts and at the same time retain a higherpercentage of the desired fibres, or similar screen meshes may be usedwith increased rates of speedr to produce comparable results, so thatibre may be cleaned and graded to a quality much above that possiblewith the previous equipment above referred to. In five months of testwork employing the apparatus of the present invention, no blinding orscreen wear has been apparent.

ri`he invention generally comprises the use of a rotatable cylindricalscreen incorporating therewithin a pair of beaters rotated in oppositedirections, one of which is rotated in the direction of rotation of thescreen which latter is disposed at an incline and, through the medium ofrotating spaced apart inter-meshing beaters combined with said rotatablescreen, the clumps of fibre are caused to break up, as to free theshorts and dust, and throw the fibre with substantial force against thescreen surface so that by continual repetition of this action, newsurfaces of the bre are exposed to the screen which, due to its rotatingaction, ensures that continuously new and clean screening cloth isavailable for screening and that all the libre is thoroughly' mixed andreceives uniform treatment.

The invention will lbe fully understood by reference to the followingdetailed specification taken in conjunction with the accompanyingdrawings, in which,

FIG. l is a fragmentary perspective view of the screening apparatus ofthe present invention showing a practical arrangement of cooperativeparts operatively arranged to perform the improved screening functionsof the present invention.

FIG. 2 is a longitudinal section taken through the apparatus disclosedin FIG. l; and

FIG. 3 is a transverse section taken substantially along the line 3 3 ofFIG. 2.

Referring to the drawings, and particularly to FIG. 1 in the iirstinstance, A indicates the apparatus as a whole which incorporates arotary screen supporting frame 10 adjustably mounted on the frameworkbase 11 as by pivoting frame 10 at 12 from one end thereof, andsupporting it at the other end by the pivotally mounted screwthreadedadjusting shafts 13, screw-threadedly engaged with the brackets 14 onthe 'basev supporting frame 11 whereby the inclination of the screensupported by frame 10 may be adjusted to the required degree. The rotarycylindrical screen unit B is rotatably supported on frame 1t) by meansof a super-structure comprised of the end frames l5 and 16,respectively, which carry the bearing rollers 17 and 1S, respectively,which in conjunction with other bearing rollers suitably mounted, suchas the rollers 19 and 20 mounted in pairs, serve to engage suitableroller bearing tracks disposed at the ends of the framework forpermitting rotatable support of the screen unit B. The rotatable supportof the screen also includes end thrust roller 20a engaging flange 2017.

The screen unit B is driven through a suitable power source effectingrotation of the drive shaft 21 through its driving sprocket which mesheswith the drive chain 21a in turn driving the sprocket 22 of driven shaft23 which is supported in suitable bearings on the sub-framework andwhich in turn drives the gear 24 keyed thereto and which meshes with thelixed chain gear 25 rigidly carried by one end of the screen unit B, Thescreen unit B is enclosed within the casing C, the lower part of whichis formed as a receiver 26 for the screened material having a suitablecontrol discharge member 27 through which the screen material isdischarged in suitable rnanner. The screen unit C is fed through thefeeding conduit D which passes through an end enclosure 29 of i screenunit C and which connects the screen unit with a generally designated bythe letters E and F, are disposed in cooperative rotatable relation.These beaters are generally comprised by the shafts 30 and 31,respectively, which extend longitudinally throughout the length of thescreen unit C and carry a plurality Vof beater bars 32 and 33,respectively, for each shaft which preferably may constitute three orfour in number radially arranged in respect to each shaft and designedin effect to inter-mesh with each other as each shaft 32 and 33 rotatein opposite directions to one another. These beaters are'disposed moreclosely adjacent to the bottom of screen unit than to the top as isclear from a consideration of FIG. 3,V and their height is suitablyadjustable to meet desired requirements in any suitable manner.

The beaters E and F are preferably rotated by' means y of apower sourceseparate to that driving the screen unit B and which rotates the beaterdriving shaft 34 carrying a driving sprocket which meshes with the drivechain 35 and which in turn operates the driven sprocket 36 carried bybeater shaft F. Beater shaft E is in turn driven by means of a suitablegear 37 carried by beater in a clockwise direction and beater 30 in acounter-clockwise direction, while the drum unit is rotated atapproximately 12 r.p.rn. in a clockwise direction. Alternatively, ofcourse, the direction of rotation of these rotary eleshaft F which inturn is designed to mesh with the gear ments could be reversed. Inresult, therefore, the beat- 33 carried by beater Shaft E so that as aresult, the ers have the effect of lifting the feed from the bedupbeaters E and F are rotated in opposite directions. These wardiYbetween the beaters and 0f throwing Seid ma' shafts are jonrnalled in asuitable bearing supporting block terial forcefully upwardly andoutwardly against the driirn 38a mounted on the sub-frame 39 and whiehby means surface as to rapidly break up said material into screenof aremovable shim 40 may be elevated or lowered as 10 able libres. Thisbreaks up the lumps of fibre, freeing required to set the spacing ofshafts E and F in relation to the Shorts and the dust and by repeatingthis action exthe bottom 0f screen unit B, or to change theirinclinaposes continually new surfaces of the fibre to the screen. tionin respect to the screen unit B as may be desired, The rotating screenensures that continual new and clean it being understood that theopposite ends 0f shafts E screening cloth is available for screening andthat all the and F are likewise supported, The end plates 29 0f the 15fibre is thoroughly mixed and receives uniform treatment. housingsurrounding screen unit B are provided with ln this way, the remarkablyimproved results have been the twin vertically arranged slots 41 forpassage there. achieved over prior methods and smaller screen meshesthrough of shafts 30 and 31 of beaters E and F and which may be used toremove the same quantity of dust and accordingly permit of verticaladjustment of these shafts shorts while at the same time retaining ahigher peras may be required. Adjustment of the drive chain for centege0f the desired iibreS- Alternatively, Similar shaft 31 of beater F maybe accomplished in any suitable Screen meshes may be used as in the pastbut with insimple Way Such as by means of the slotted quadrant creasedrates of speed to produce comparable results and bracket 42 attached tothe mounting plate carrying the the bre can be cleaned and graded to aquality much bearing of drive shaft 34. above that possible withprevious conventional equipment.

The screen unit C may be formed from any simple suitin iVe nlOntllS 0fteSt werk, n0 blinding 0r Screen weer able framework basicallyconstituted by the cylindrical w35 encounteredend rings 43 and 44 (FIG.2) having the radially spaced By comparison with conventional ar Screenequipapart longitudinally extending frame bars 45 and internient endUsing the Seine Screen ineen, tile apparatus 0f vening rings or hoops46, all of which may be welded or the Present invention with 45% greaterfeed Inte reotherwise secured to form a framework over which the rnOVed205% aS Compared t0 165% 0f SiIOrtS and dnSt screen 47 is fitted andsecured at the ends by suitable The tilrnS were 21 little higher qualityindicating that rings 48. At the discharge end of the cylindrical screenequal qualities and quantities can be removed at approxiunit C, thehousing includes a suitable casing 49 forming mately 50% greater rate 0ffeed- Comparable areas of a reservoir with a discharge outlet 50 forreceiving from Screen ClOtil were, in the CaSe 0f tile PresentinVenticn, 24 the screen unit, nnsereened material, square feet asagainst 50 square feet in the conventional In operation, the screen unitB is disposed at an innat screen, illustrating three times greatereiciency per cline to the horizontal on its framework with the feedsquare foot of cloth in favor of the apparatus of the presend (at theleft as viewed in FIG. 2) being raised relacnt invention as compared tothe conventional fiat screen tively to the opposite discharge end sothat the feed introequipment. A comparison between the results of theduced at the drum unit via the feeding conduit D, at a present inventionand those obtained on the conventional predetermined rate, will build upon the base of the screen dat Screen heretofore generally used is givenin the followalong its length to a depth higher than the lowermost ingTables l to 3, wherein the present invention is desigreach of the beaterbars 32 and 33. The beaters 30 nated as the T.E.C. rotary screen and theprior art pracand 31 are rotated at approximately 380 r.p.m., beater 31tice as the hat screen:

TABLE #l T.E.C. rotary versus #I3 Hall screen- AK fibre N 13 T.E.C.Rotary Screen Conventional Flat Screen T.E.C. Rotary Screen o. Hall TestScreen Beatcr Drum Type of Run Rate Rate Spoed Speed Beaters ScreenOvers Thrus oi Overs Thrus of Feed Feed Set; oi two Each Four 14 MeshLot i# 144 lbs. 6 oz. 281bs. 10 oz. (15 min.) 119 lbs. 31 lbs. (9 mln.)Arms-Round 301 5% Diam. 93.4% 16.6% 692 lbs/hr. 79.4% 20.6%1,0001bs./l1r. L, 20 Mesh 1.3131:2 279 lbs. 42 lbs. (15 min.) 134 lbs.4G lbs. (8 min. 20 sec.) P4 o s :I l 2 E. f 86.9% 13.1% 1,284 ibs/hr.74.4% 25.6% 1,291 1bn/hr. e; E lei a.: 'L 280.51bs. 51 lbs. (12% min.)110 ibs. 30 lbs. (5 min.) m f i g 84.6% 15.4% 1,490 lbsJhr. 78.0% 21.4%1,680 lbs/hr. 0 m .g 2 5 248 lbs. 18 lbs. (4 min.) 219 lbs. 21 lbs. (3min. 45 scc.) Q* O 83.2% 6.8% 3,990 lbs/hr. 90.4% 9.6% 3,5041bs./hr.

O El N i# 193 lbs. 24 lbs. (8 min.) 192 lbs. 28 lbs. (7% min.) 88.9%11.1% 1,628 lbs/hr. 87.3% 12.7% 1,760 lbs/hr.

Average of 4 Tests (Lots #SO2-305) 11.6% 2,123 lbs/hr. 17.3% 2,060lbs/hr.

TABLE #2 Test Sample Length, Percent -8 -200 Inch mi" Mesh Mesh Lot FiatHeads .12e 64. 7 29. o es. o 301 Screen Thrus 077 88. 2 13. 0 39. 2Overs 136 56. 4 29. 3 19. 7 Calcul. Overs 136 60.0 32. 2 19. 8

TEC Heads 126 64. 7 29. 0 23.0 Screen Thrus 983 84. 4 13. 7 34. 1 Overs29 59. 9 29. 4 18. 8 Calcul. Overs .137 59.6 33.0 20.1

Lot Flat Heads 125 67.1 28. 9 29. 5 302 Screen Thrus 074 80. 8 11. 4 42.7 Overs .133 01. 9 30. 6 27. 0 Calcul. Overs .133 63.5 31. 6 27.5

TEO Heads 125 67. 1 28. 9 29. 5 Screen Thrus 075 90. 2 l2. 0 46. 1 Overs127 62. 7 34. 5 24. 3 Calcul. Overs .142 59.2 34.8 23.8

Lot Flat Heads 119 67.7 18. 8 46. 7 303 Screen Thrus 069 94. 9 7. 5 54.6 Overs .117 68.6 21. 43. 8 Calcul. Overs .128 62.8 20.9 45. 3

TEC Heads 119 67. 7 18. 8 46. 7 Screen Thrus 069 95. 1 5. 6 67. 3 Overs114 70. 5 23. 5 40.3 Calcul. Overs .133 60.3 22.4 41.1

Lot Flat Heads .140 57. 8 40. 1 13.9 304 Screen Thrus 066 97. 12. 9 38.0 Overs 132 59. 3 35. 8 14. 8 Calcul. Overs 145 55.0 42. 1 12.2

TEC Heads 139 59. 5 36. 8 13. 2 Screen Thrus 071 93. 0 11. 0 44. 5 Overs135 59. 4 41. 3 13. 2 Calcul. Overs 146 56.0 39. 6 9. 9

Lot Flat Heads .144 56. 7 35.0 22. 5 305 Screen Thrus 067 96. 5 10. 940.6 Overs 132 62. 0 38. 5 20. 4 Calcul. Overs .154 51.8 38.0 20.3

TEC Heads .126 59. 8 34. 8 24. 6 Screen Thrus 074 90. 3 14. 4 48. 9Overs 161 52. 4 36. 8 20.4 Calcul. Overs 134 55. 3 37. 7 21.1

TABLE #3 Average 0f 4 Tests (Lots #3M-305, incl.)

Test Sample Length, Percent -8 -200 inch li s" Mesh Mesh Flat HeadSample .132 62.3 30.7 28.2 Screen Thrus 069 94. 9 10. 7 44.0 Overs 12963. 0 31. 5 26. 5 Calcul. Overs .140 58.3 33.2 26.3

TEC Head Sample .127 63.5 29.8 28.5 Screen Thrus .072 92.3 10.8 51. 7Overs 134 61. 3 34.0 24. 6 Calcul. Overs 139 57. 7 33. 6 24. 0

A consideration of Table #1 indicates that Using the same screen mesh asconventional equipmeimthe T.E.C. screen, with 45% greater feed rate,removed 20.6% vs. 16.6% of shorts and dust. These throughs were a littlehigher quality, indicating that equal qualities and quantities can beremoved at approximately 50% greater rate of feed. The comparable .areasof screen cloth were T.E.C. 24 sq. ft. vs. conventional 50 sq. ft. TheT.E.C. screen is, therefore, three times as efficient per square foot ofcloth as conventional equipment A consideration of Table #2 in respectof quality shows that using the average of lots 302 to 305 inclusive,which were run at the same feed rates, and with 24 mesh screens on theT.E.C. vs. 14 mesh on the conventional, the T.E.C. screen removed 17.3%vs. 11.6% of shorts and dust. These throughs contained 7.7% more -200mesh dust, and were the equivalent in other respects to the conventionalscreen throughs.

A consideration of Table #3 illustrat that the overs 6 or final productincreased in average length to .134" vs. .129" with lower short (1/16)content-61.3 vs. 63.0. The Bauer-McNett or wet screen analysis confirmedthe above results, showing increased length (-8 mesh)- f 34.0 vs. 31.5,and a lower dust content (-200 mesh) 24.6 vs. 26.5.

The advantageous results of the present invention are, therefore,clearly evident from the foregoing resulting in substantially increasedcapacity, a product having a quality much above that possible withprevious equipment, with apparatus which consumes about 50% less powerinvolving approximately 50% less weight, while taking up approximatelyone quarter of the space previously required by the dat screen method,whereas diiculty of blinding and work stoppage as well as screen wear isgreatly reduced. The invention makes it possible to employ Smallerscreen meshes to remove the same quantity of dust and shorts whileretaining a higher percentage of desired fibres or similar screen meshesmay be used with increased rates of feed to produce comparable results.

What I claim as my invention is:

1. Apparatus for screening asbestos bres comprising an inclinedrotatably supported cylindrical screen, means for introducing asbestosfibre concentrate therewithim to form a moving bed along the bottom ofsaid screen, means for rotating said screen, a pair of beaters extendinglongitudinally through the interior of said cylindrical screen and belowthe centre longitudinal axis thereof, said beaters having a plurality ofradially spaced apart beater elements, said beaters when mounted havingsaid beater elements disposed in staggered relation to those of theother and capable of interlapping the beater elements of each other inspaced apart relation to one another when said beaters are rotated, saidbeater elements being capable of entering said bed of libre concentrate,and means for rotating said beaters in opposite directions to oneanother to cause upward movement of fibre concentrate between saidbeaters and to forcefully discharge said concentrate upwardly andradially outwardly against said screen, and means for rotating saidscreen.

2. Apparatus for screening asbestos libres comprising a cylindricalscreen, means for rotatably supporting said screen at an incline to thehorizontal to provide a feeding end raised above the oppositedischarging end thereof, a plurality of beaters rotatably mounted toextend within said screen parallel to one another and parallel to andbelow the central longitudinal axis of said screen, said beaters havingbeating elements thereon, said clements of one beater being disposed instaggered relationship to those of an adjacent beater when mounted linside by side relationship and capable of interlapping the elements of anadjacent beater in spaced apart relation to one another, means forfeeding asbestos fibre concentrate to said screen at the feeding `endthcreofto form a moving bed of fibre concentrate along the bottom ofsaid screen, means for rotating said adjacent beaters at substantialspeed and in opposite directions to one another as to lift asbestosconcentrate from said bed inwardly and upwardly between said beaters anddischarge it forcefully radially outwardly against said screen, meansfor rotating said screen at alower rate than said beaters, means forcollecting fibres passing through said screen, and means for collectingunscreened libres at the discharge end of said screen.

3. Apparatus for screening asbestos fibres as claimed in claim 2 inwhich the beaters comprise a'plurality of shafts extendinglongitudinally within the screen from one end to the other and thebeater elements comprise a plurality of longitudinally extendingcircumferentially l spaced apart beater bars connected to said shaftsand 728,759 disposed -in radially spaced apart relation thereto. 796,7947,646 References Cited in the le of this patent 1 7 782 UNITED STATESPATENTS 6 2,536,054 233,829 Adi Nov. 2, 1880 2,543,537

8 Pillrnore et al May 19, 1903 Bauer Aug. 8, 1905 Boughton May 10, 1910Little Dec. 22, 1931 Harrington Jan. 2, 1951 Smith Feb. 27, 1951

